This invention relates to elimination of chlorohydrins from hydrolyzates prepared from vegetable proteins hydrolyzed with concentrated hydrochloric acid.
Recent studies have shown that non-decoloured liquid seasonings prepared by hydrolysis of vegetable proteins with concentrated hydrochloric acid contain a considerable quantity of chlorohydrins, including in most cases a dominant proportion of 1,3-dichloro-propan-2-ol. The problem of their elimination arises. Various processes may be considered for eliminating these components.
It has been found in particular that pastes obtained by concentrating these seasonings by evaporation or versions of these seasonings obtained by decolouring with active carbon have distinctly lower concentrations of chlorohydrins. However, concentration by evaporation involves a considerable consumption of energy. Similarly, decolouration with active carbon in filter presses, for example, not only involves high outlay on the necessary operations and plant, it also considerably modifies the organoleptic qualities of the seasoning which loses its characteristic taste while retaining its flavour enhancing power.
Another possibility is to hydrolyze a starting material which does not contain any fats, glycerol being precisely the precursor which enables chlorohydrins to be formed with hydrochloric acid. Now, on the one hand, starting materials such as these are more or less commercially unobtainable and, on the other hand, would significantly modify the organoleptic qualities of the seasoning.
Hydrolysis could also be carried out with a chlorinefree mineral acid, such as sulfuric acid or phosphoric acid. However, such a modification of the traditional process would also have adverse affects upon the organoleptic qualities of the seasoning obtained.
Yet another possibility is to separate a fraction of the hydrolyzate containing the chlorohydrins by rectification. However, a process such as this involves at least two separation steps if it is desired to retain in particular in the end product components which perform an important organoleptic function but which are more volatile than the chlorohydrins.